HEALTHCARE

 Diarrhea. An increased frequency of defecation due to a microbial pathogen and defined as greater than 3 stools per day or greater than 200 g of stool per day.
B. Epidemiology
1. Infectious diarrhea is the most common cause of diarrhea worldwide.
2. The second most common cause of death worldwide but the leading cause of childhood death worldwide.
3. In the United States, most episodes occur during the winter months and are due to viral pathogens (eg, noroviruses, rotaviruses).
C. D iarrhea Syndromes
1. Acute infectious diarrhea. Lasting less than 14 days.
a. Acute watery diarrhea without blood
b. Acute dysentery (diarrhea with blood)
2. Chronic or persistent diarrhea. Lasting more than 14 days.
D. Pathogenesis. Pathogens are transmitted through contaminated water or foods/food products and reach the gastrointestinal tract to cause:
1. Increased intestinal secretion of fluid and electrolytes, most commonly in the small intestine, through the production of enterotoxins (eg,cholera toxin, Escherichia coli heat labile and heat stable toxins) that may mediate secretagogues (eg, 5-hydroxytryptamine [5-HT]).
2. Decreased intestinal absorption of fluid and electrolytes in the small and large intestine through intestinal mucosal damage. Severe villous atrophy can occur with infection due to Giardia, Cryptosporidium, Cyclospora, and Microsporidium (intestinal protozoa). An alternative cause of villous atrophy is celiac disease (an autoimmune disorder due to gluten intolerance).
CAUSES OF INFECTIOUS DIARRHEA.
 A. Bacterial1. Campylobacter jejuni. Most commonly from a foodborne exposure to
poultry.
 2. Salmonella spp
     a. Nontyphoid. Most commonly from a foodborne exposure to poultry or eggs.
     b. Typhoid and paratyphoid. Person-to-person contact during international travel.
3. Shigella spp. Person-to-person contact.
4. Shiga toxin–E coli (0157:H7). Most commonly a foodborne exposure to undercooked beef or raw seed sprouts.
5. Vibrio spp
   a. Cholera. Low level of endemicity in U.S. Gulf Coast states with transmission by water exposure or seafood exposure.
  b. Noncholera. Most commonly foodborne exposure to shellfish and seafood.
6. Yersinia enterocolitica. Can be associated with swine and cattle exposure.
7. Aeromonas spp. International travel to tropical regions.
8. Plesiomonas shigelloides. International travel and ingestion of seafood.
9. Staphylococcus aureus. Foodborne exposure (eg, potato salad) due to preformed toxin.
10. Clostridium perfringens. Contaminated meat, vegetables, or poultry
with bacterial spores.
11. Bacillus cereus. Contaminated rice (reheated rice) and vegetable sprouts with bacterial spores.
12. Clostridium difficile.
B. Viruses. Most commonly occur during the winter months and are typically due to outbreaks in families, nursing homes, or day care centers (usually selflimiting
and less than one day).
1. Noroviruses.
2. Rotavirus.
3. Enteric adenoviruses (types 40 and 41).
4. Cytomegalovirus (CMV). More common in immunocompromised patients.
C. Parasites. Most commonly related to international travel and/or contaminated
water. Diarrhea usually persists for greater than 7 to 10 days.
1. Giardia intestinalis
2. Cryptosporidium parvum
3. Cyclospora cayetanensis
4. Microsporidia spp
5. Entameba histolytica. (Africa, Asia, Latin America).
6. Balantidium coli. (Asia).
Clinical Manifes tations of Infectious Diarrhea(SYMPTOMS).
 A. D iarrhea. Usually one of two forms, but there can be considerable overlap.
1. Watery diarrhea without blood. Usually self-limiting and clinically nonspecific to etiology.
2. Diarrhea with blood (dysentery). Usually indicates colitis (ie, inflammatory diarrhea). Associated with fever, nausea, and abdominal pain and cramps. Most commonly due to Shigella, Campylobacter, nontyphoid Salmonella, and Shiga toxin–E coli. Also, can be associated with Aeromonas spp, Yersinia spp, noncholeraic Vibrio, and E histolytica.
B. Abdominal Pain and Cramps. Usually associated with dysentery but can also occur without dysentery.

C. N ausea and Vomiting. May be associated with abdominal pain and cramps but is typically due to viral illnesses.
D. F ever. Usually occurs with acute dysentery (ie, inflammatory diarrhea) or bacteremia from salmonella.
E. T enesmus. May indicate inflammatory diarrhea and is characterized as a feeling of a constant need to defecate.
F. D elirium or Altered Mental Status. Usually indicates dehydration and is usually associated with other findings such as tachycardia, dry mucous membranes,and poor skin turgor.

 Approach to the Patient.A. H istory. A complete history should be performed with attention to exposures or risk factors associated with infectious diarrhea, comorbid illnesses
(immunocompromised or pregnant patients may be at risk for certain infections), medications, recent travel history, and occupation (eg, day care or nursing home worker). Additionally, diarrhea in family members and the timing of diarrhea onset may be helpful:
1. Incubation period less than 6 hours. (S aureus or B cereus.)
2. Incubation period 6 to 24 hours. (C perfringens or B cereus.)
3. Incubation period 16 to 72 hours. (All other causes.)
B. Physical Examination. A complete physical examination should be performed
with focused attention on:
1. Neurologic examination (to assess mental status by the Glasgow coma cale).
2. HEENT examination (dry mucous membranes can suggest dehydration).
3. Cardiovascular examination (resting tachycardia or orthostatic hypotension may suggest dehydration).
4. Musculoskeletal examination (joint pain may suggest Yersinia spp or
C jejuni as Reiter syndrome).
5. Rectal examination (to detect blood in the stool that may indicate dysentery).
Because the most feared complication of infectious diarrhea is dehydration, the clinical evaluation of the degree of dehydration remains important. (The followingare general considerations that would vary among different patients.)
1. Mild-to-Moderate Dehydration (3% to 9% Fluid Loss)
  a. Fatigue and restlessness
  b. Dry mucous membranes and thirst sensation
  c. Weak pulses and cool extremities
  d. Decreased urine output (may be indicated by a dark-concentrated urine and with less than 800 mL per day)
2. Severe Dehydration (Greater than 10% Fluid Loss)
   a. Apathy and lethargy
   b. Dry mucous membranes, sunken eyes, and extreme thirst sensation
   c. Deep breaths and tachycardia
  d. Skin tenting, poor capillary refill, weak pulses, and cool extremities
  e. Minimal urine output (less than 500 mL dark-concentrated urine per day)
 C. Laboratory Studies
1. CBC(COMPLETE BLOOD COUNT). Nonspecific. An elevated hematocrit may suggest dehydration.
2. BMP. Infectious diarrhea may produce a non–gap metabolic acidosis in association with electrolyte abnormalities (eg, hypernatremia, hypokalemia). An elevated BUN, creatinine, and metabolic alkalosis may suggest dehydration.
3. Blood cultures. Usually not ordered and of low yield; however, bacteremia may occur with Salmonella spp–related infections.
4. Stool leukocytes and/or lactoferrin. May be helpful for inflammatory diarrhea, but nonspecific.
   a. Stool leukocytes. Sensitivity 73% and specificity 84% for bacterial infectious diarrhea. A small content of stool mucus or liquid stool is stained with methylene blue stain or Wright stain and then examined for leukocytes. A false-negative test may occur with cytotoxogenic
C difficile or E histolytica infection due to destruction of leukocytes.
  b. Stool lactoferrin. Sensitivity 92% and specificity 79% for bacterial infectious diarrhea. Lactoferrin is a glycoprotein found in neutrophil granules and is detected by a rapid immunologic latex agglutination method. The test performance is not altered by the destruction of
leukocytes.
5. Stool cultures. The diagnostic yield is estimated from 1% to 5%. Indicated when patients have any of the following:
  a. Severe diarrhea (greater than 6 stools per day)
  b. Dysentery
  c. Diarrhea associated with fever
  d. Persistent diarrhea (over more than 7 days)
 e. Multiple cases of diarrhea
TREATMENT
A. Supportive Care. Should be provided in all cases and can consist of fluid and electrolyte replacement, a diet of easily digestible foods (eg, BRAT diet: bananas, rice, applesauce, and toast), and/or antimotility medications (eg, loperamide). Antimotility medications should be avoided in patients with dysentery or suspected inflammatory diarrhea. Patients should avoid milk or other dairy products due to the development of transient lactose intolerance.
B. Oral Rehydration Therapy. The initial treatment of infectious diarrhea should focus on the prevention of dehydration with rehydration efforts. Commercialformulations (eg, Pedialyte) can be  obtained and used according to the listed directions; however, as a general rule, a homemade oral rehydration solution can be produced by the following formula: add 1 tablespoon of salt and
2 tablespoons of sugar to 1 liter of water.Treatment recommendations according to the degree of dehydration include the following. (These are general rules to the approach to rehydration
and may not apply to all patients.)
1. Minimal Dehydration (Less than 3% Fluid Loss)
  a. Less than 10 kg weight: 60–120 mL of oral rehydration solution per diarrhea stool
  b. Greater than 10 kg weight: 120–240 mL of oral rehydration solution per diarrhea stool
2. Mild-to-Moderate Dehydration (3% to 9% Fluid Loss)
  a. May be treated as an outpatient
  b. 50–100 mL per kg of body weight replaced over a 3- to 4-hour period of time